Reference is hereby made to U.S. Pat. No. 3,604,116, the subject matter thereof being incorporated herein.
U.S. Pat. No. 3,604,116, issued to H. Shpuntoff, a co-inventor herein, discloses a dental impression wafer having a sheet carrier of strong pliable material sandwiched between deformable impression material such as bite wax. The wafer permits a precise visual indication of premature engagement of the teeth and bite deflection. The wafer however does not permit measurement of monitoring of the bite force and force exerted on the wafer by the patient during occlusal analysis, which analysis may suggest left/right muscular disbalance due possibly to premature contact or deflected contact between teeth of the maxilla and mandible. The force exerted during an occlusal analysis can now be monitored, and permanent records of the force exerted on either side of the mouth are readily obtainable. These records may be used to later compare the patient's muscle activity before and after correction and adaptation.
Briefly, the invention comprises a thin metallized film of polymer material having piezoelectric properties, the film being coated on all surfaces and edges with a conventional dental impression material, typically bite wax. The polymer film is preferably KYNAR.RTM. piezofilm, a polyvinylidene fluoride product of Pennwalt Corporation, Philadelphia, Pa., assignee of the present invention, although copolymers of vinylidene fluoride have been found to work satisfactorily.
The wax retains visible impressions of the relative positions and shapes of the tooth crowns, as well as bite deflection and premature teeth engagement indicia. The wax should deform plastically without affecting the spatial relationship of the teeth, and normally such condition obtains if the carrier sheet thickness is maintained below about 0.025 mm, although the abovementioned patent suggests a value no greater than about 0.020 mm. The piezoelectric film material, on the other hand, permits force measurements to be precisely continuously monitored, which measurements may be permanently recorded by conventional means. If the carrier film (piezoelectric film) thickness is greater than about 0.025 mm, an artificial prematurity may result.